Cement, cement products, molding material, a concrete member and a method of producing the same

ABSTRACT

Cement comprising hydraulic cement and polymer precursor such as alcohol-soluble phenol resin precursor that is substantially anhydrous and generates water by polymerization.

This application is a division of application Ser. No. 08/427,341, filedApr. 24, 1995, abandoned, which is a continuation of application Ser.No. 08/129,590, filed Sep. 30, 1993, now abandoned.

BACKGROUND OF THE INVENTION

This invention relates to improvement on cement, products thereof, andmolding material to yield higher physical strength, better thermalresistance and water resistance, and a method for producing them.

This invention also relates to an improvement on a concrete member toyield higher physical strength, better thermal resistance and waterresistance, and a method of producing the same.

There are known various organic or inorganic compounds available formolding materials, adhesives, laminates and other materials used forvarious fields such as civil engineering and construction industries,transportation industries of cars or railroads, chemical industries,other general mechanical industries and so on.

Hydraulic cement has been generally used as mortar or concrete mainly incivil engineering and construction industries. The cement is combinedwith more than 25 weight % of water and aggregate is added thereto toproduce cement products. The cement products have low flexural strengthof 50 to 100 kgf/cm² (5 to 10 N/mm²) although they have high compressivestrength and they conventionally have reinforcing bars used therein. Inorder to improve the flexural strength of the cement products, there areadded short glass fibers or carbon fibers thereto. However, theirflexural strength rarely exceeds 400 kgf/cm² (40 N/mm²)

In general, the cement products have higher physical strength as theamount of water used is lowered, and also as the amount of blow-holesincluded therein is lowered.

For example, Japanese Application Publication No. 43431/1984 disclosescement products having extremely high flexural strength without anyfibers included therein and without being molded under high compressivepressure. These cement products can be produced by kneading hydrauliccement, water and water organic polymer with each other while highshearing force is applied thereto by a double roller mill so that sizesand rates of blow-holes in the cement products are limited.

The cement products disclosed in The Japanese Application Publicationhave higher flexural strength because it is cured by combining hydrauliccement with 7 to 30% of water relative to hydraulic cement. However, thecement products, although having flexural strength improved,disadvantageously have physical strength lowered when they are immersedin water. They also have water resistance lowered due to their swellingwhen they are immersed in water. The disadvantages are present becauseof the cement products including water organic polymer.

In order to improve water resistance of the cement products, JapanesePatent Application Laying-Open No. 206342/1988 discloses cement productsincluding an isocyanate compound reacted with the hydrophilic group ofthe water organic polymer of the aforementioned cement products. Suchisocyanate compound my be added to the components of the cement productsbefore they are kneaded or while they are kneaded. Also, they may beimpregnated with isocyanate compound after they are headed, but beforethey are cured or after they are cured.

However, such material has a disadvantage during kneading and moldingbecause isocyanate compound is virulent and has a strong irritatingsmell. Furthermore, urethane derivative which is the main reactantproduced by reacting the isocyanate compound with the hydrophilic groupdisadvantageously has lower thermal resistance.

Formaldehyde has been used also for molding materials, adhesives andlaminates. Such molding material including formaldehyde is obtained bycombining formaldehyde resin precursor with filler such as wood flour,pulp, diatomaceous earth or the like, curing agent, lubricant, coloringagent and/or other additives, grinding and classifying them. In order tolower fragility of such molding material and improve flexural strengththereof, there has been added thereto filler of fibers such as cottonfibers, flax fibers, glass fibers or the like.

Such molding material is molded by compression molding, transfer moldingor injection molding to produce mold goods. Such mold goods haveflexural strength of 500 to 1000 kgf/cm² (50 to 100 N/mm²) unless thereis used filler of fiber material such as glass fibers or flax fibers.

However, such molding material of formaldehyde cannot have high flexuralstrength of more than 100 N/mm² without any filler of reinforcingfibers. If reinforcing fibers are added to formaldehyde, then thereinforcing fibers are cut when the molding material is produced andoriented when it is molded. The cutting and orienting of the fiberscauses the mold goods to have the physical strength varied and anorientation provided thereto.

In addition, since the molding material has fluidity lowered due to thefilled fibers, the molding material disadvantageously fails to pervadeall parts of the mold, which prevents the molded products from having asmooth surface.

Conventional concrete members have been manufactured by placing freshlymixed concrete in a mold of steel, wood or FRP provided in factories orworking spots. It will be noted that they may be advantageouslymanufactured by using permanent molds of precast concrete because suchpermanent molds are integral to the concrete members and not required tobe removed. If the permanent mold is formed of concrete having highdurability, then the entire concrete members will have durabilityimproved. The concrete members may have reinforcing bars used therein.

However, conventional concrete placed in the mold of steel, wood or FRPhas poor wear resistance and water tightness. Furthermore, the concretemembers will have durability lowered due to rust of the reinforcingbars. This is caused by chloride permeating the concrete members throughfine cracks or honeycombs therein, which are in turn produced due topoor operation of the concrete construction or poor curing of concretematerial therefor.

Although the property of concrete itself may be improved by addingadmixtures such as fibers or silica fumes to concrete material, suchimprovement on the entire concrete members is undesirably expensive.

Although the entire concrete members are able to have their durabilityimproved if permanent molds of precast concrete having high durabilityare used, they still have no flexural strength improved.

Such permanent molds of precast concrete are relatively thicker andheavier, which causes assemblies thereof to be troublesome. Of late, theconcrete members are required to be relatively thinner and lighter.

SUMMARY OF THE INVENTION

It is therefore desirable to provide cement having higher flexuralstrength and better water resistance and better thermal resistance;cement products having higher physical strength, such as flexuralstrength of more than 40 N/mm², higher elastic modulus, and betterthermal resistance and better water resistance; molding materialincluding a cement component and having higher physical strength, suchas flexural strength of more than 50 N/mm² and preferably of more than100 N/mm², higher elastic modulus, and better thermal resistance andbetter water resistance; an inexpensive concrete member having higherflexural strength and higher durability such as water tightness,chemical resistance and salt damage or weather resistance; and a methodof producing a concrete member having higher flexural strength andhigher durability such as Water tightness, chemical resistance and saltdamage or weather resistance.

Accordingly, the present invention provides cement that has at least onekind of hydraulic cement and a polymer precursor that is substantiallyanhydrous and generates water by a curing reaction.

The polymer precursor may be blended with a ratio of 10 to 60 parts byweight and preferably 12 to 30 parts by weight relative to 100 parts byweight of the hydraulic cement.

The polymer precursor may be formaldehyde resin precursor such as phenolresin precursor, melamine resin precursor or urea resin precursor orpolyimide resin precursor.

In accordance with another aspect of the invention, there is providedcement that has at least one kind of hydraulic cement, a polymerprecursor that is substantially anhydrous and generates water by acuring reaction, and an additive.

The additive may be polyamide such as fatty alcohol soluble polyamide orpolyacrylamide.

Filler such as fiber material may also be added to the cement of thepresent invention.

When filler is added, the polymer precursor may be blended with the sameratio as aforementioned, but the blend ratio is set while the hydrauliccement has filler included.

In accordance with a further aspect of the invention, there is provideda cement product formed by curing cement that has at least one kind ofhydraulic cement and a polymer precursor that is substantially anhydrousand generates water by a curing reaction.

In this aspect, the polymer precursor may be blended with the same ratioas aforementioned and may be added with additive and/or filler.

In accordance with a further aspect of the invention, there is provideda molding material that has at least one kind of hydraulic cement and apolymer precursor that is substantially anhydrous and generates water bya curing reaction.

In this aspect, the polymer precursor may be blended with a ratio of 5to 100 parts by weight and preferably 7 to 60 parts by weight relativeto 100 parts by weight of the hydraulic cement.

Also, in this aspect, the polymer precursor may be formaldehyde resinprecursor such as phenol resin precursor, melamine resin precursor orurea resin precursor, but may be polyimide precursor. It should be notedthat the blend ratio of polymer precursor is set while it has no alcoholsolvent included.

In accordance with a further aspect of the invention, there is provideda method of producing molding material by mixing composite including atleast one kind of hydraulic cement and a polymer precursor that issubstantially anhydrous and generates water by a curing reaction, wherethe composite being in the form of powder.

In accordance with a further aspect of the invention, there is provideda method of producing molding material by mixing composite including atleast one kind of hydraulic cement and a polymer precursor that issubstantially anhydrous and generates water by a curing reaction, wherethe polymer precursor is in a thermal molten form.

In accordance with a further aspect of the invention, there is provideda method of producing molding material by mixing composite including atleast one kind of hydraulic cement and a polymer precursor that issubstantially anhydrous and generates water by a curing reaction, wherethe polymer precursor is in the thermal molten form and the composite isground and classified.

In accordance with a further aspect of the invention, there is provideda method of producing molding material by mixing composite including atleast one kind of hydraulic cement and polymer precursor that issubstantially anhydrous and generates water by curing reaction, thepolymer precursor being in the form of alcohol solution of the polymerprecursor.

In accordance with a further aspect of the invention, there is provideda method of producing molding material by mixing composite including atleast one kind of hydraulic cement and polymer precursor that issubstantially anhydrous and generates water by curing reaction, thepolymer precursor being in the form of alcohol solution of the polymerprecursor and the composite being ground and classified after thealcohol is evaporated.

In these aspects of producing molding material, the polymer precursormay be blended with a ratio of 5 to 100 parts by weight and preferably 7to 60 parts by weight relative to 100 parts by weight of the hydrauliccement.

Also, in these aspects, the polymer precursor may be formaldehyde resinprecursor such as phenol resin precursor, melamine resin precursor orurea resin precursor, but may be polyimide precursor. It should be notedthat the blend ratio of polymer precursor is set while it has no alcoholsolvent included.

In accordance with another aspect of the invention, there are providedmolded products obtained by molding, heating and curing molding materialcomprising composite including at least one kind of hydraulic cement anda polymer precursor that is substantially anhydrous and generates waterby curing reaction.

In this aspect, the composite may be in the form of powder. It may be ina thermally molten form of polymer precursor or in the thermally moltenform of polymer precursor and ground and classified.

Alternatively, it may be in a form of alcohol solution of polymerprecursor or in the form of alcohol solution of polymer precursor andground and classified.

Also, in this aspect, the polymer precursor may be blended with a ratioof 5 to 100 parts by weight and preferably 7 to 60 parts by weightrelative to 100 parts by weight of the hydraulic cement.

Furthermore, in this aspect, the polymer precursor may be formaldehyderesin precursor such as phenol resin precursor, melamine resin precursoror urea resin precursor, but may be polyimide precursor. It should benoted that the blend ratio of polymer precursor is set while it has noalcohol solvent included.

In accordance with another aspect of the invention, there is provided aconcrete member comprising a concrete body and at least one reinforcingbody integrally provided with the concrete body, the reinforcing bodyincluding at least one kind of hydraulic cement and polymer precursorthat is substantially anhydrous and generates water by curing reaction.

In this aspect, the reinforcing body may be attached to the concretebody or buried in the concrete body.

Also, in this aspect, the polymer precursor may be blended with a ratioof 5 to 100 weight parts relative to 100 weight parts of the hydrauliccement.

Furthermore, in this aspect, the polymer precursor may be formaldehyderesin precursor such as phenol resin precursor, melamine resin precursoror urea resin precursor, but may be polyimide precursor. It should benoted that the blend ratio of polymer precursor is set while it has noalcohol solvent included.

In accordance with a further aspect of the invention, there is provideda method of producing a concrete member by forming at least onereinforcing body including at least one kind of hydraulic cement andpolymer precursor that is substantially anhydrous and generates water bycuring reaction, placing the reinforcing body in a mold, and placing andcuring freshly mixed concrete in the mold to form the concrete memberwith the reinforcing body integrally provided.

In accordance with a further aspect of the invention, there is provideda method of producing a concrete member by forming at least onereinforcing body including at least one kind of hydraulic cement andpolymer precursor that is substantially anhydrous and generates water bycuring reaction; assembling a permanent mold of the reinforcing body;and placing and curing freshly mixed concrete in the permanent mold toform the concrete member with the reinforcing body integrally provided.

In accordance with a further aspect of the invention, there is provideda method of producing a concrete member by forming a concrete body;forming at least one reinforcing body including at least one kind ofhydraulic cement and polymer precursor that is substantially anhydrousand generates water by a curing reaction; adhering the reinforcing bodyto the concrete body by adhesive to form the concrete member.

In these aspects of producing a concrete member, the polymer precursormay be blended with a ratio of 5 to 100 weight parts relative to 100weight parts of the hydraulic cement.

Furthermore, in these aspects, the polymer precursor may be formaldehyderesin precursor such as phenol resin precursor, melamine resin precursoror urea resin precursor, but may be polyimide precursor.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects and features of the invention will beapparent from the description of the embodiments of the invention andthe accompanying drawings.

FIG. 1 is a perspective view of a concrete member constructed inaccordance with one embodiment of the invention;

FIG. 2 is a cross sectional view of a concrete member together with amold in which the concrete member is formed in accordance with onemethod of the invention;

FIG. 3 is a cross sectional view of a concrete member constructed inaccordance with another embodiment of the invention;

FIG. 4 is a cross sectional view of a concrete member together with apermanent mold in which the concrete member is integrally formed inaccordance with another method of the invention; and

FIG. 5 is a cross sectional view of a concrete member together with amold in which the concrete member is formed in accordance with a furthermethod of the invention.

DETAILED DESCRIPTION OF THE EMBODIMENT

The invention provides cement comprising at least one kind of hydrauliccement and a polymer precursor that is substantially anhydrous andgenerates water by a curing reaction.

As the cement comprises a polymer precursor that is substantiallyanhydrous and generates water by a curing reaction, water generated bythe curing reaction hydrates with the hydraulic cement. This causeshigher physical strength such as flexural strength and better waterresistance and thermal resistance of the composite material.

Hydraulic cement used in the invention may be conventional cement suchas Portland cement (normal Portland cement, high early strength Portlandcement or moderate Portland cement, for example), blended cement(Portland blast furnace cement, silica cement or fly-ash cement, forexample), special cement (aluminous cement or oil well cement, forexample) and various gypsum. One or more kinds of hydraulic cement canbe used.

The polymer precursor that generates water when cured may be suitablyformaldehyde resin precursor or polyimide precursor. The precursor mayhave a predetermined viscosity adjusted by solvent in view of moldingthereafter.

The formaldehyde precursor may be a phenol resin precursor, melamineresin precursor or urea resin precursor, preferably in the form ofalcohol solution with a nonvolatile component of 40 to 70%. Alcoholwhich may be used in this invention is methanol, ethanol, propanol,butanol, cyclohexanol, phenol, cresol, ethylene glycol, trimethyleneglycol or the like.

The polyimide precursor my be preferably in the form of solution forwhich a solvent of N-methyl-2-pyrrolidone or N,N-dimethyl acetamide orthe like is used with a nonvolatile component of 10 to 30% includedtherein.

Polymer precursor in the form of solution and hydraulic cement areblended with a blending ratio of 10 to 60 weight parts of polymerprecursor to 100 weight parts of hydraulic cement. Preferable blendratio is of 12 to 30 weight parts of polymer precursor. If hydrauliccement has filler added, then the blend ratio of polymer precursor is to100 weight parts of powder components of hydraulic cement having thefiller added.

If the blend ratio of polymer precursor is less than 8 weight parts,then it will not be able to be positively blended with hydraulic cement.This also causes the resultant product to have lower physical strength.

If the blend ratio of polymer precursor is more than 60 weight parts,the resultant product has cracks and physical strength is not optimized.Therefore, it will be noted that more than 60 weight parts of polymerprecursor is not economical.

There may be blended additive or filler with composite material ofpolymer precursor and hydraulic cement, if necessary. Such additive orfiller may be blended by a conventional mixer such as an Eirich typemixer or a helical mixer. If the blend ratio of polymer precursor isrelatively small, it may be preferably blended by a mixer providing acompression function, shearing function or spatula touching function.Such a mixer may be a header, a wet pan mill, a helical rotor, a rollermill, a Banbury type mixer or the like.

The kneaded cement composite material is molded by roller molding,extruder molding, press molding or pouring molding. The polymerprecursor of the cement composite material is then heated and cured toform a cement product having a predetermined configuration and size.

Composite material including formaldehyde precursor may be heated at atemperature of 100° to 300° C. and preferably at a temperature of 150°to 250° C. Composite material including polyimide precursor may beheated at a temperature of 300 to 500° C. and preferably at atemperature of 350° to 450° C. Heating composite material cures polymerprecursor and generates water, whereby hydraulic cement hydrates so thatthe cement product has higher physical strength.

In general, formaldehyde precursor is rapidly cured in an acid area ofless than pH 7, but it will be able to be fully cured even in an alkaliarea of more than pH 7 if it is heated at a temperature of 150° to 250°C. for a relatively longer time.

It is known that such curing reaction of formaldehyde precursor is mademainly by the following model condensation reaction: ##STR1##

The thus generated water hydrates hydraulic cement under heat to producea cement hydrate.

It is known that polyimide precursor becomes an insoluble and infusiblesolid of excellent thermal resistance when it is heated at a temperatureof more than 300° C. through an intramolecular cyclodehydrationreaction.

An example of a typical curing reaction of polyimide precursor thatproduces polyimide of excellent thermal resistance in accordance withintramolecular cyclodehydration reaction of polyamic acid havingpyrromerit acid skeleton follows: ##STR2##

Water generated by imide reaction of polyamide precursor hydrateshydraulic cement under heat in the same manner as water generated bycuring reaction of formaldehyde precursor to produce a cement hydrate.

A cement product has texture formed by the rigid three-dimensionalbridge structure of formaldehyde resin or polyimide and cement hydrateinvolved with each other, which causes the product to have higherphysical strength.

Although cement formed in the aforementioned has higher flexuralstrength provided thereto by heating, it has been found that some of thecement products of the invention have higher physical strength providedthereto by immersing in water after curing by heating.

Although the cement of the invention has no water particularly requiredon kneading, it may be blended with small quantity of water inconsideration of premolding. Furthermore, there may be added thereto anadditive such as glycerol, glycerol triacetate, polyethylene glycol,furfural, dibutyl phthalate, phthalic anhydride, stearic acid, rosin,polyimide, polyacrylamide, polyvinyl alcohol or the like.

Particularly, polyimide, polyacrylamide or polyvinyl alcohol is apreferable additive for improvement of the cement product. The additivemay be added directly to the polymer precursor and then dissolved ordispersed therein, but it may be dissolved or dispersed in solvent suchas ethanol, methanol or N,N-dimethylacetamide and then added to polymerprecursor.

A blend ratio of the additive may be generally of 0.5 to 20 weight partsto 100 weight parts of polymer precursor and preferably 2 to 12 weightparts thereto.

Polyamide used in the invention is preferably alcohol-soluble. Suchalcohol-soluble polyimide may be amide bonding --CON-- having at least apart of hydrogen substituted by methoxymethyl group, or amidebonding--CON(R) produced from a secondary amine. Such polyimide added tothe polymer precursor reacts with the polymer precursor during heatingand curing in the manner corresponding to that in which formaldehyderesin precursor or polyimide precursor reacts through intramolecularcyclodehydration under heat.

Furthermore, cement composite material of the invention may be blendedwith filler when headed, if necessary. A blend ratio of filler may bedetermined in view of formability of composite material and physicalstrength of the obtained product. Filler may be of conventional sand,light-weight aggregate, wood flour, ground calcium carbonate, aluminiumhydroxide which may be used as incombustible agent for plastic orrubber, inorganic pigment or the like.

In order to further improve the physical strength of the cement productsof the invention, there may be used hydraulic cement having particlesize distribution adjusted in multiple mode. Hot press curing the cementproducts under pressure to adjust blow-holes thereof may also be used.

In order to improve adhesion of filler and/or hydraulic cement to resin,there may be added conventional silane coupling agent thereto. Suchsilane coupling agent may be γ-aminopropyl triethoxysilane,γ-ureidopropyl triethoxysilane or γ-grycidoxypropyl trimethoxysilane.

Some examples of the invention and some comparisons will be describedhereinafter.

EXAMPLES 1 to 3

There were kneaded 100 weight parts of hydraulic cement which was formedof normal Portland cement, alumina cement (tradename DENKA AluminaCement No. 1 manufactured by Denki Kagaku Kogyo Kabushiki Kaisya, Japan)or blend thereof, 23 weight parts of alcohol-soluble phenol resinprecursor (tradename Shonol manufactured by Showa Highpolymer Co., Ltd.,Japan) and 2.3 weight parts of glycerol in a mortar mixer for 6 minutes.The thus kneaded mixture passed through a pair of rollers, used as aknoodle maker and having a revolution ratio identical to each other,about 20 times to form a sheet-like strip of 1.5 mm thickness. This wasdivided into sheet-like articles of about 25 mm width and 75 mm length.10 sheet-like products were heated and cured at a temperature of 150° C.for 18 hours to make cement products.

5 cement products thereof were provided directly for bending tests whilethe remaining 5 cement products were provided for bending tests afterthey were immersed in water of 20° C. for three days. The bending testswere made in accordance with JIS (Japanese Industrial Standard) R 5021with a distance of 50 mm between supporting points where the cementproducts were supported. Table I shows the results of the bending tests.The flexural strengths of the cement products were measured immediatelyafter they were heated at a temperature of 150° C. (referred to asdirect test in Table I) or immersed in water.

                  TABLE I                                                         ______________________________________                                                    Ex 1      Ex 2   Ex 3                                                         COMPOSITION                                                       ______________________________________                                        normal Portland                                                                             100         60     0                                            cement                                                                        alumina cement                                                                              0           40     100                                          phenol resin  23          23     23                                           precursor                                                                     glycerol      2.3         2.3    2.3                                          flexural strength (Kgf/cm.sup.2)                                              direct test   466         545    572                                          after immersion                                                                             460         581    599                                          in water                                                                      ______________________________________                                    

EXAMPLE 4

There were kneaded 100 weight parts of alumina cement (tradename DENKAAlumina Cement No. 1 manufactured by Denki Kagaku Kogyo KabushikiKaisya, Japan) or blend thereof, 15 weight parts of alcohol-solublephenol resin precursor (tradename Shonol manufactured by ShowaHighpolymer Co., Ltd., Japan) and 1.5 weight parts of glycerol in abench type header for 6 minutes. The thus headed mixture was molded in apushing mold under pressure of 150 kgf/cm² to form cement products of 10mm thickness, 40 mm width and 160 mm length. The cement products wereheated and cured at a temperature of 150° C. for 18 hours to make cementproducts.

5 cement products thereof were provided directly for bending tests. Thebending tests were made in accordance with JIS R 5021 with a distance of100 mm between supporting points where the cement products weresupported. The resultant flexural strengths of them were 529 kgf/cm².

EXAMPLE 5

The same materials as in Example 4 were used. 100 weight parts ofalumina cement, 20 weight parts of alcohol-soluble phenol resinprecursor and 1.8 weight parts of glycerol were headed in a bench typekneader for 6 minutes. The thus kneaded mixture was molded in a vacuumextruding molding machine to form cement products of 15 mm thickness, 20mm width and 160 mm length. The cement products were cured and providedfor bending tests in the same manner as in EXAMPLE 4. The resultantflexural strengths of them were 551 kgf/cm².

EXAMPLES 6 to 10

Cement products were manufactured in the same manner as in Examples 1 to3 except for fillers of N-methoxymethyl-polyimide having hydrogen ofamide bonding substituted by methoxymethyl group by about 30% (tradenameToresin manufactured by Teikoku Chemical Industries Co., Ltd., Japan)and ethanol additionally used and blend ratios thereof set as indicatedin Table II. The cement products were provided for bending tests in thesame manner as in Examples 1 to 3. The results of the tests were TableII.

                  TABLE II                                                        ______________________________________                                                   Ex 6   Ex 7   Ex 8     Ex 9 Ex10                                              COMPOSITION                                                        ______________________________________                                        normal Portland                                                                            100      40     40     0    0                                    cement                                                                        alumina cement                                                                             0        60     60     100  100                                  phenol resin 21.6     23     20     21.6 13.6                                 precursor                                                                     polyamide    1.4      0.8    0.8    1.4  1.4                                  ethanol      0        0      3.2    0    8.0                                  glycerol     2.3      2.3    2.0    2.3  2.3                                  flexural strength (Kgf/cm.sup.2)                                              direct test  584      713    628    762  357                                  after        561      720    640    785  378                                  immersion                                                                     in water                                                                      ______________________________________                                    

EXAMPLES 11 to 13

Cement products were manufactured in the same manner as in Examples 1 to3 except for fillers of polyacryl amide (tradename Acoflock N100Smanufactured by Mitsui Sianamiddo Co., Ltd., Japan) or polyvinylalcohol(tradename Gosenol manufactured by Nippon Gosei Kagaku Kogyo KabushikiKaisya, Japan) in addition to N-methoxymethyl-polyimide (tradenameToresin manufactured by Teikoku Kagaku Kogyo Kabushiki Kaisya, Japan) ofExamples 6 to 10 additionally used and blend ratios thereof set asindicated in Table III. The cement products were provided for bendingtests in accordance with JIS R 5021 with a distance of 50 mm betweensupporting points where the cement products were supported. The resultsof the tests were Table III.

                  TABLE III                                                       ______________________________________                                                    Ex 11     Ex 12   Ex 13                                                       COMPOSITION                                                       ______________________________________                                        alumina cement                                                                              100         100     100                                         phenol resin  21.6        21.6    21.6                                        precursor                                                                     polyamide     1.4         --      --                                          polyacrylamide                                                                              --          1.4     --                                          polyvinylalcohol                                                                            --          --      1.4                                         glycerol      2.3         2.3     2.3                                         flexural strength (Kgf/cm.sup.2)                                              direct test   1160        1320    650                                         ______________________________________                                    

EXAMPLE 14

There were kneaded 100 weight parts of alumina cement (tradename DENKAAlumina Cement No. 1 manufactured by Denki Kagaku Kogyo KabushikiKaisya, Japan) and 20 weight parts of polyamide precursor (tradenameU-varnish-A manufactured by Ube Kosan Co., Ltd., Japan) and molded inthe same manner as in Examples 1 to 3. The thus kneaded mixture washeated and cured at a temperature of 120° C. for one hour, at 150° C.for 20 minutes, at 200° C. for 20 minutes, at 250° C. for 20 minutes andfinally at 350° C. for one hour to form cement products.

The cement products were provided directly for bending tests. Thebending tests were made in accordance with JIS R 5021 with a distance of50 mm between supporting points where the cement products weresupported. The resultant flexural strengths of them were 402 kgf/cm².

EXAMPLES 15 to 18

The cement products obtained in the same manner as in Examples 6 and 9were heated at a temperature of 200° C. for 18 hours or at 300° C. for 6hours.

The cement products were provided for bending tests in the same manneras in Examples 1 to 3. In the tests, the flexural strengths of thecement products were measured before heated, after heated and afterimmersed in water in order to compare them. The results of the tests areindicated in Table IV.

                  TABLE IV                                                        ______________________________________                                                Ex 15 Ex 16          Ex 17 Ex 18                                      ______________________________________                                        kind of   normal Portland    alumina cement                                   cement    cement                                                              heating   200     300        200   300                                        temp.                                                                         (°C.)                                                                  flexural strength (kgf/cm.sup.2)                                              before    584     584        762   762                                        heated                                                                        after     713     792        1040  1120                                       heated                                                                        after     706     785        1060  1220                                       immersed                                                                      in water                                                                      ______________________________________                                    

COMPARISONS 1 and 2

The cement products of about 4 mm thickness having high flexuralstrength commercially available from a certain Japanese Company weredivided into 9 pieces, three of which were provided for bending tests.

In order to determine thermal resistance of the cement products, eachthree remaining pieces were heated at a temperature of 200° C. for 18hours and at a temperature of 300° C. for 6 hours, respectively and thenprovided for bending tests.

The bending tests were made in accordance with JIS R 5021 with adistance of 50 mm between supporting points where the cement productswere supported. The results of the bending tests were indicated in TableV.

                  TABLE V                                                         ______________________________________                                                COMPARISON 1                                                                              COMPARSION 2                                              ______________________________________                                        heating   200           300                                                   temp.                                                                         (°C.)                                                                  flexural strength (kgf/cm.sup.2)                                              before    1390          1390                                                  heated                                                                        After     462           330                                                   heated                                                                        ______________________________________                                    

It will be noted that the cement products of Examples 1 to 18 of theinvention had higher flexural strength and better thermal resistance andwater resistance in comparison with the cement products of Comparisons 1and 2.

This invention further provides molding material comprising at least onekind of hydraulic cement, a polymer precursor that is substantiallyanhydrous and generates water by curing reaction, and additives and/orfillers, if necessary. The molding material has no water substantiallyadded thereto.

The molding material of the invention has flexural strength of more than50 N/mm² and in some examples has flexural strength of more than 100N/mm² even though it has no reinforcing fibers filled therein.

The molding material may be produced by mixing the composite material ina thermally molten form and thereafter grinding and classifying thesame.

Otherwise, the molding material may be produced by mixing the compositematerial in the form of an alcohol solution of the polymer precursor andthereafter grinding and classifying it with or without alcoholevaporated.

The polymer precursor used is preferably formaldehyde resin precursor,but it may be polyimide precursor. The formaldehyde precursor may be aphenol resin precursor, melamine resin precursor-or urea resinprecursor, being substantially anhydrous and generating water by heatingand curing. This means that the precursor potentially includes water. Inthis invention, "Substantially anhydrous" means that water content ofthe polymer precursor is less than 5%, preferably less than 4% and mostpreferably less than 2% relative to the weight of hydraulic cement. Thewater content may be measured by Karl-Fischer Method (AnalyticalChemistry Manual issued by Association of Japan Analytical Chemistry in1971, pages 31 and 32). If the water content of the polymer precursorexceeds 5%, then the hydraulic cement will be cured or weathered duringmanufacturing or storing the molding material, which causes the physicalstrength of the mold goods to be lowered.

The hydraulic cement to be used in the molding material of the inventionmy be conventional cement such as Portland cement, blended cement,special cement and various gypsum which may be identical to those usedin the cement composite material of the invention aforementioned. One ormore kinds of hydraulic cement can be used. The hydraulic cement may beused as commercially available, but it has particle distributionadjusted in multi mode or particle configuration rounded in order toimprove the physical strength or fluidity of the molding material.

The formaldehyde precursor used in the molding material of the inventionmy be blended with hydraulic cement in accordance with moldability andother properties of the mold goods. In general, a blend ratio offormaldehyde precursor may be 5 to 100 weight parts and preferably 7 to60 weight parts to 100 weight parts of hydraulic cement. If the blendratio of formaldehyde precursor is less than 5 weight parts, then theblended condition of the components and the fluidity of the moldingmaterial is lowered and the mold goods have defects produced therein. Ifit is more than 100 weight parts, then the mold goods disadvantageouslyhave cracks found therein and physical strength is not optimized. Theblend ratio of formaldehyde resin precursor is set while it has noalcohol included therein.

The molding material of the invention is preferably blended with amadditive of polymer having acid amide bonding such as polyimide orpolyacryl, for example, in order to improve the properties of the moldgoods.

In general, a blend ratio of the additive may be 0.5 to 30 weight partsand preferably 2 to 20 weight parts relative to 100 weight parts offormaldehyde precursor. If it is less than 0.5 weight parts, then thereappears no improvement in the properties of the mold goods. Also, if itis more than 30 weight parts, there is not an economical increase in theproperties of the mold goods.

The additive is preferably finely ground before blended. When it is tobe blended using alcohol, the polyimide is preferably alcohol-soluble.Such alcohol-soluble polyimide may be amide bonding --CONH-- having atleast a part of hydrogen substituted by methoxymethyl group, or amidebonding --CON(R)-- produced from a secondary amine.

The molding material of the invention may be blended with otheradditives such as conventional lubricant, silane coupling agent orcoloring agent in addition to the aforementioned polyimide. Thelubricant may be formed of glycerol, glycerol triacetate, phthalicanhydride, furfural, alkyl phenol, zinc stearate, magnesium stearate,rosin or the like. The silane coupling agent may be γ-aminopropyltriethoxysilane, γ-ureidopropyl triethoxysilane or γ-grycidoxypropyltriethoxysilane. The coloring agent may be formed of organic orinorganic pigment such as aniline black, carbon black or titanium oxide.

Furthermore, the molding material of the invention may be blended withfiller. Such filler may be a conventional one such as wood flour, pulp,cotton flock, stone dust, ground calcium carbonate, aluminium hydroxide,sand, light-weight aggregate, glass fibers, carbon fibers or the like.The polymer precursor my have the blend ratio thereof increased as theamount of the filler increases.

A method for manufacturing the molding material of the invention willnow be described.

Formaldehyde precursor, hydraulic cement and additive are blended so asto uniformly disperse their components to form the molding material ofthe invention. They may be blended by a conventional mixing machine suchas a mortar mixer, a header, a blender or a roller machine. The propermixing machine may be preferably selected in accordance with the blendratio of the components as described below.

A first mixing system is one in which the components in the form ofpowder may be mixed at the normal temperature by a conventional coldmixing machine such as a header, a mortar mixer or a blender. Thecomponents may be finely ground or dispersed in a small quantity ofsolvent such as methanol or ethanol in order to effectively prevent thecomponents from being scattered. The mixture in the form of powder maybe dried, if necessary, to obtain the molding material.

A Second mixing system is one in which the components in the molten formare thermally mixed by a conventional thermal mixing machine such as aBanbury type mixer, a kneader or a hot roller machine, which is heatedby a steam heater or an electric heater. A temperature at which thecomponents are heated is so set that the formaldehyde precursor is fullymolten, but no reaction converting it to methylene significantlyprogresses. In general, the preferable temperature is 80° to 150° C. Ifit exceeds 150° C., the formaldehyde precursor is cured too much beforethe components are fully mixed.

The mixture which is obtained by thermally mixing the components isdried, ground and classified to form the molding material.Alternatively, the mixture which is obtained by thermally mixing thecomponents is used as the molding material without grinding andclassifying because of a molding method and/or product configuration inmanufacturing the mold goods.

A third mixing system is one in which the components in the form ofalcohol solution of formaldehyde precursor may be mixed by aconventional mixing machine such as a header, a Banbury type mixer, amortar mixer or a two-roller machine.

In general, this mixing is made at the normal temperature, but it may bemade while alcohol is heated nearly at its boiling temperature in orderto enhance evaporation of alcohol if the components are fully dispersedin alcohol.

Formaldehyde precursor used for the molding material is alcohol-solubleand it is used in an alcohol solution. A quantity of alcohol usedtherefor may be determined in view of the dispersion effect of thecomponents and moldability of the molding material. Preferably, it maybe an alcohol solution having 20 to 80% nonvolatile component.

The alcohol which is used in the molding material of this invention maybe methanol, ethanol, propanol, butanol, cyclohexanol, phenol, cresol,ethylene glycol, trimethylene glycol or the like.

The mixture which is obtained by mixing the components is dried toevaporate the alcohol, if necessary, and then ground and classified toform the molding material. Alternatively, the mixture which is obtainedby mixing the components is used as the molding material withoutgrinding and classifying because of a molding method and/or productconfiguration in manufacturing the mold goods.

The thus obtained molding material may be molded by compression molding,transfer molding, injection molding, extrusion molding, flowing-inmolding (pouring molding) or the like and heated during or after moldingto form the mold goods. A heating temperature may be 100° to 300° C. andpreferably 150° to 250° C. The heat cures the formaldehyde resinprecursor and generates water, which causes the hydraulic cement tohydrate to yield higher physical strength. This higher physical strengthresults from aluminium ion ion-bridging with resin, which is caused by asmall quantity of water generated therein.

Although, in the aforementioned, formaldehyde resin precursor is used asthe polymer precursor, it should be understood that polyimide precursormay be used as the polymer precursor.

The molded products manufactured by the invention may be applied forvarious uses. They may be used for transportation fields such as bodies,ship parts, pallets or the likes, electronic or electric fields such asinstrument housings, insulation parts, IC sealers, parabola antennas,printed circuit boards, floors for office automation devices or thelike, public engineering or construction fields such as concretereinforcing materials, concrete molds, composite molds such assuperstrong composite molds, paving materials, tiles, water tanks,roofing materials (roofing tile, roofing slate and others), inner orouter wall materials, ceiling materials, partition wall materials,columns for road, capsule houses, light-weight manholes, artificialmarble products such as kitchen counters or washing stands or the like,chemical industry fields such as tanks, pipes, pipe covering or the likeand general machine fields such as gears or the like.

Some examples of the molding materials of the invention and onecomparison will now be described.

EXAMPLES 19 and 20

There were blended and mixed alumina cement (tradename DENKA AluminaCement No. 1 manufactured by Denki Kagaku Kogyo Kabushiki Kaisya, Japan)phenol resin precursor (tradename Shonol BRG-558 manufactured by ShowaHighpolymer Co., Ltd., Japan), hexamethylene tetramine, zinc stearate,furfural and coloring agent (tradename BAYERTITAN manufactured by BayerJapan Co., Ltd., Japan) by a roller mill for rubber which was heated ata temperature of 110° C. by steam. A revolution ratio of rollers was setat 1 to 1.3. The water content of phenol resin precursor measured byKarl-Fischer method was 0.1%.

Dough mixture which was wound on the rollers of the roller mill wasremoved from the rollers and ground in a stainless steel mortar to formthe molding material. The molding material was filled in a die having120° C. maintained and compressively molded under 10 N/mm². Thereafter,the die temperature was raised to 180° C. and maintained at thistemperature for 6 hours to form sheet-like mold goods of about 3 mmthickness.

The sheet-like mold good was divided into 10 pieces of 15 mm width and80 mm length. 5 pieces thereof were provided directly for bending testswhile remaining 5 pieces were provided for bending tests after they wereimmersed in water of 20° C. for seven days. The bending tests were madeby a bisecting point loading method with a distance of 60 mm betweensupporting points where the pieces were supported. Flexural elasticmodulus was determined by measuring flexure at the middle of the testedpieces.

The composition of Examples 19 and 20 are indicated at Table VI-I andthe results of the tests are shown in Table VI-II.

                  TABLE VI-I                                                      ______________________________________                                                Ex 19     Ex 20     Ex 21                                                     Composition                                                           ______________________________________                                        alumina   100         100       100                                           cement                                                                        phenol    25.0        16.6      22.0                                          resin     (BRG-558)   (BRG-558) (BKM-2620)                                    precursor                                                                     h e x a - 2.50        1.66      --                                            methylene-                                                                    tetramine                                                                     zinc      0.50        0.33      0.22                                          stearate                                                                      furfural  --          1.60      --                                            coloring  3.00        --        --                                            agent                                                                         ______________________________________                                    

                  TABLE VI-II                                                     ______________________________________                                                Ex 19     Ex 20   Ex 21                                               ______________________________________                                        flexural strength (N/mm.sup.2)                                                before    130         102     58.0                                            immersion                                                                     in water                                                                      after     153         105     not measured                                    immersion                                                                     in water                                                                      flexural elastic modulus (kN/mm.sup.2)                                        before    33.8        35.3    not measured                                    immersion                                                                     in water                                                                      after     33.1        35.1    not measured                                    immersion                                                                     in water                                                                      water absorption rate after immersion in water %                                      0.19      0.21    not measured                                        ______________________________________                                    

EXAMPLE 21

There were ground in a stainless steel mortar alumina cement (tradenameDENKA Alumina Cement No. 1 manufactured by Denki Kagaku Kogyo KabushikiKaisya, Japan) and phenol resin precursor (tradename Shonol BKM-2620manufactured by Showa Highpolymer Co., Ltd., Japan) and added theretozinc stearate in the form of powder in a mortar mixer for four minutesto form molding materials. The water content of phenol resin precursormeasured by Karl-Fischer method was 4.5%. The molding materials weremolded to form testing pieces in the same manner as in Examples 19 and20.

The composition of Example 21 is indicated in Table VI-I and the resultof the test is shown in Table VI-II.

EXAMPLES 22 to 25

There were blended and premixed normal Portland cement, alumina cement(tradename DENKA Alumina Cement No. 1 manufactured by Denki Kagaku KogyoKabushiki Kaisya, Japan), phenol resin precursor (tradename ShonolBRS-330 manufactured by Showa Highpolymer Co., Ltd., Japan, with 60.6%of nonvolatile component included therein and water content of 1.3%),polyimide including amide bonding--CONH--having at least a part ofhydrogen substituted by methoxymethyl group (tradename Toresinmanufactured by Teikoku Chemical Industries Co., Ltd., Japan), glyceroland silane coupling agent (tradename KBE-903 manufactured by Shin-EtsuChemical Co., Ltd., Japan) in a mortar mixer for-two minutes.Thereafter, they were mixed for four minutes in a roller mill for rubberhaving a revolution ratio of a pair of rollers of 1 to 1.2.

Dough mixture which was wound on the rollers of the roller mill wasremoved from the rollers to form sheet-like molding materials of about 2mm thickness. The sheet-like molding materials were compressively moldedin a die of 80° C. under compression stress of 6 N/mm² and heated at atemperature of 200° C. for 15 hours to form sheet-like mold goods.

The sheet-like mold good was divided into 10 pieces of 25 mm width and100 mm length, which were provided for tests identical to those inExamples 19 and 20.

The composition of Examples 19 and 20 are indicated in Table VII-I andthe results of the tests are shown in Table VII-II. The tested pieceswere subject to X-ray diffraction in which there were found no peak incement hydrate.

                  TABLE VII-I                                                     ______________________________________                                                  Ex 22 Ex 23      Ex 24   Ex 25                                                Composition                                                         ______________________________________                                        normal      100     60         --    --                                       Portland                                                                      cement                                                                        alumina     --      40         100   100                                      cement                                                                        phenol      18.4    19.3       21.2  21.2                                     resin                                                                         precursor                                                                     polyamide   1.6     1.7        1.8   1.8                                      glycerol    2.0     2.2        2.3   2.3                                      coupling    --      --         --    2.3                                      agent                                                                         ______________________________________                                    

                  TABLE VII-II                                                    ______________________________________                                                  Ex 22 Ex 23      Ex 24   Ex 25                                      ______________________________________                                        flexural strength (N/mm.sup.2)                                                before      104     165        191   204                                      immersion                                                                     in water                                                                      after       70.5    156        212   208                                      immersion                                                                     in water                                                                      flexural elastic modulus (kN/mm.sup.2)                                        before      45.4    47.8       38.5  39.3                                     immersion                                                                     in water                                                                      after       40.7    44.9       34.5  35.1                                     immersion                                                                     in water                                                                      water absorption rate after immersion in water %                                        1.57  0.34       0.16    0.15                                       ______________________________________                                    

EXAMPLES 26 to 29

There were blended and mixed in addition to components in Example 23melamine resin precursor (manufactured by Mitsui Toatsu Chemicals, Inc.,Japan having 74.6% of nonvolatile component included therein and watercontent of 4.3%) in the form of alcohol solution as the formaldehyderesin precursor and polyacrylamide as the additive in such compositionas shown in Table VIII-I. After the components were premixed in a benchtype kneader for two minutes, they were mixed for four minutes in aroller mill for rubber having a revolution ratio of a pair of rollers of1 to 1.2.

Dough mixture which was wound on the rollers of the roller mill wasremoved from the rollers to form sheet-like molding materials of about 3mm thickness. The sheet-like molding materials were rolled several timesthrough a roll mill having a revolution ratio of 1 to 1 until it had athickness of about 1.5 mm and heated at a temperature of 200° C. for 15hours to form sheet-like mold goods. The sheet-like mold good wasdivided into 10 pieces of 25 mm width and 100 mm length, which wereprovided for tests identical to those in Examples 19 and 20.

The composition of Examples 26 to 29 are indicated in Table VIII-I andthe results of the tests are shown in Table VIII-II.

                  TABLE VIII-I                                                    ______________________________________                                                 Ex 26 Ex 27      Ex 28   Ex 29                                                Composition                                                          ______________________________________                                        normal     100     --         --    --                                        Portland                                                                      cement                                                                        alumina    --      100        100   100                                       cement                                                                        phenol     30.0    21.2       21.2  --                                        resin                                                                         precursor                                                                     melamine   --      --         --    18.0                                      resin                                                                         precursor                                                                     polyamide  --      1.6        --    4.0                                       polyacrly- --      --         1.6   --                                        amide                                                                         glycerol    3.0    2.3        2.3   4.0                                       ______________________________________                                    

                  TABLE VIII-II                                                   ______________________________________                                                  Ex 26 Ex 27     Ex 28   Ex 29                                       ______________________________________                                        flexural rigidity (N/mm.sup.2)                                                before      71.1    112       125   33.5                                      immersion                                                                     in water                                                                      after       64.0    126       103   not                                       immersion                           measured                                  in water                                                                      flexural elastic modulus (kN/mm.sup.2)                                        before      28.4    32.8      32.7  not                                       immersion                           measured                                  in water                                                                      after       27.1    30.5      28.4  not                                       immersion                           measured                                  in water                                                                      water absorption rate after immersion in water %                                        2.16  0.42      0.63    not                                                                           measured                                    ______________________________________                                    

EXAMPLE 30 and COMPARISON 3

The mold goods of Example 27 were heated at a temperature of 300° C. forsix hours and provided for bending tests to determine thermalresistance. In comparison, mold goods of about 4 mm thickness havinghigh flexural strength that are commercially available from a certainJapanese Company were divided into pieces of 25 mm width and 75 mmlength, heated at the same temperature for the same time and providedfor bending tests.

Table IX shows flexural strength of the tests.

                  TABLE IX                                                        ______________________________________                                                  Ex 30 COMPARISON 3                                                  ______________________________________                                        flexural strength (N/mm.sup.2)                                                before      112     136                                                       heated                                                                        after       106     32.4                                                      heated                                                                        ______________________________________                                    

It will be noted that the mold goods of Examples 19 to 30 had higherflexural strength and elastic modulus, and better thermal resistance andwater resistance in comparison with the mold goods of Comparisons 3.

This invention further provides a concrete member having a concrete bodyand reinforcing body disposed on a surface of the concrete body or inthe concrete body. The reinforcing body comprises at least one hydrauliccement, a polymer precursor such as formaldehyde precursor or polyimideprecursor that is substantially anhydrous and generates water by acuring reaction, and an additive and/or filler, if necessary.

The reinforcing body may be disposed on or in the concrete body byvarious methods such as a burying method or permanent mold method, whichwill be described in detail.

The hydraulic cement used in the reinforcing body of the invention my beconventional cement such as Portland cement, blended cement, specialcement and various gypsum which may be identical to those used in thecement composite material or molding-materials of the inventiondescribed with reference to Examples 1 to 30. One or more kinds ofhydraulic cement can be used.

The polymer precursor is preferably formaldehyde resin precursor, but itmay be polyimide precursor.

The formaldehyde resin precursor used for the reinforcing body of theinvention my be phenol resin precursor, melamine resin precursor or urearesin precursor, having substantially no water, but adapted to generatewater by heating and curing.

The formaldehyde resin precursor used for the reinforcing body of theinvention is alcohol-soluble and it is used in an alcohol solution.Alcohol which is used in the reinforcing body of this invention my bemethanol, ethanol, propanol, butanol, cyclohexanol, phenol, cresol,ethylene glycol, trimethylene glycol or the like.

The formaldehyde resin precursor for the reinforcing body of theinvention is blended with hydraulic cement in accordance withmoldability and other properties of the reinforcing body. In general, ablend ratio of formaldehyde resin precursor may be 5 to 100 weight parts(excluding alcohol) to 100 weight parts of hydraulic cement. If theblend ratio of formaldehyde resin precursor is less than 5 weight parts,then the blended condition of the components will be made worse and thereinforcing body has defects. If it is more than 100 weight parts, thereinforcing body disadvantageously has cracks produced therein andphysical strength is not optimized.

The reinforcing body of the invention is preferably blended with anadditive of polymer having acid amide bonding such as polyimide orpolyacryl, for example, in order to improve the properties of thereinforcing body.

In general, a blend ratio of the additive may be 0.5 to 30 weight partsand preferably 2 to 20 weight parts relative to 100 weight parts offormaldehyde resin precursor. If it is less than 0.5 weight parts, thenthere will appear no improvement in the properties of the reinforcingbody while if it is more than 30 weight parts, there will be noeconomical improvement in the properties of the reinforcing body (in thesame manner as the cement and the mold goods of the invention describedwith respect to Examples 1 to 30).

The reinforcing body of the invention my be blended with other additivesuch as conventional lubricant, silane coupling agent or coloring agentin addition to the aforementioned polyimide. Lubricant may be glycerol,glycerol triacetate, phthalic anhydride, furfural, alkyl phenol, zincstearate, magnesium stearate, rosin or the like. The silane couplingagent may be γ-aminopropyl triethoxysilane,γ-ureidopropyl-triethoxysilane or γ-grycidoxypropyl triethoxysilane. Thecoloring agent my be formed of organic or inorganic pigment such asaniline black, carbon black or titanium oxide. It will be noted thatthese additives are identical to those used in the cement and themolding materials of the invention with respect to Examples 1 to 30.

Furthermore, the reinforcing body of the invention may be blended withconventional filler such as wood flour, pulp, cotton flock, stone dust,ground calcium carbonate, aluminium hydroxide, sand, light-weightaggregate, glass fibers, carbon fibers or the like, which are alsoidentical to those used in the cement and the molding materials withrespect to Examples 1 to 30.

Formaldehyde resin precursor, hydraulic cement and additive and/orfiller, if necessary, are mixed in the form of powder, paste or sheet ina mortar mixer, a blender, a kneader or a hot roller machine.

Thereafter, they are molded to a predetermined shape and heated andcured. The mixture is dried, ground and classified to form material forthe reinforcing body, which may be molded by compression molding,extrusion molding or injection molding. A heating temperature may be100° to 300° C. and preferably 150° to 250° C.

A method of manufacturing a concrete member of the invention will bedescribed with reference to the accompanying drawings.

As shown in FIG. 1, a concrete member 1 constructed in accordance withone embodiment of the invention comprises a concrete body 2 and tworeinforcing bodies 3 integrally mounted on both surfaces of the concretebody 2. It should be noted that only one reinforcing product 3 may bemounted on one of the surfaces of the concrete body 2. The reinforcingbody or bodies are of such a construction as aforementioned.

As shown in FIG. 2, the reinforcing body 3 may be placed on an innerbottom of a mold 4 and freshly mixed concrete may be placed into themold 4 and cured to form the concrete body 2 integrally associated withthe reinforcing body 3.

As shown in FIG. 3, the reinforcing body 3 may be adhered by adhesiveagent 5 to the surface of the concrete body 2 which is previously formedby a mold into which freshly mixed concrete is placed.

As shown in FIG. 4, the concrete body 2 may be molded in a permanentmold 6 into which freshly mixed concrete is placed. The permanent mold 6is formed of a plate-like mold portion 7 of wood or metal and a box-likemold portion 8 of the reinforcing body which may be produced in the samemanner as the reinforcing body 3.

After the concrete body 2 is formed, only the plate-like mold portion 7is removed out of the concrete body 2. The box-like mold portion 8 ofreinforcing body is integrally mounted on the cured concrete body 2. Inorder to support the box-like mold portion 8 on the plate-like moldportion 7, there may be provided supporting members 9 which serve toprevent the box-like mold portion 8 from falling due to pressure fromfreshly mixed concrete being placed into the permanent mold 6.

Alternatively, as shown in FIG. 5, the reinforcing product 3 is placedin the mold 4 so that the reinforcing product 3 is spaced from the innerbottom of the mold 4 by a spacer not shown. Thus, it will be noted thatthe concrete body 2 has the reinforcing body 3 integrally disposedtherein.

The reinforcing body used for the concrete member of the invention myhave no surface treatment, but it preferably has roughness provided onthe surface thereof on which the concrete body is provided.

Alternately, it may have adhesive agent of epoxy resin, unsaturatedpolyester resin or the like provided on the surface thereof on which theconcrete body is mounted or a coat layer formed on the surface thereofby coating styrene-butadiene copolymer,acrylonitrile-butadienecopolymer, ethylene-vinylacetate copolymer andthe like in the form of latex or emulsion before freshly mixed concreteis placed.

Freshly mixed concrete to be placed may be normal concrete, light-weightconcrete, high strength concrete, resin concrete or mortar thereof, butit is not limited to particular concrete.

Furthermore, the concrete member of the invention may have conventionalreinforcing bars disposed therein together with the reinforcing body ofthe invention.

Some examples of the concrete member of the invention will now bedescribed.

EXAMPLE 31

There were blended and premixed 100 weight parts of alumina cement(tradename DENKA Alumina Cement No. 1 manufactured by Denki Kagaku KogyoKabushiki Kaisya, Japan), 21.6 weight parts of phenol resin precursor(tradename Shonol BRS-330 having nonvolatile component of 60.6%manufactured by Showa Highpolymer Co., Ltd., Japan), 1.4 weight parts ofN-methxymethyl polyimide having hydrogen of amide bonding substituted bymethxymethyl group by 30% (tradename Toresin manufactured by TeikokuChemical Industries Ltd., Japan) and 2.3 weight parts of glycerol in amortar mixer for two minutes.

Thereafter, they were mixed in a roller mill for rubber having arevolution ratio of 1 to 1.3 for four minutes. Dough mixture which waswound on the rollers of the roller mill was removed from the rollers.

Thereafter, it passed several times through a roller machine having arevolution ratio of 1 to 1 and was reduced to form a sheet-like productof 2 mm thickness, which was heated at a temperature of 200° C. for 18hours to form a reinforcing product.

As shown in FIG. 2, the reinforcing body of 2 mm thickness, 40 mm widthand 160 mm length was placed in the inner bottom of the steel mold of 40mm thickness, 40 mm width and 160 mm length and thereafter freshly mixednormal concrete shown in Table X was placed into the steel mold.

When 24 hours elapsed after the concrete was placed, the concrete memberwas protected in a steam atmosphere of 65° C. for four hours to producethe complete concrete member.

The concrete member having an age of 7 days was provided for bendingtest in accordance with JIS 5201.

As the result of the bending test, the flexural strength of the concretemember was 17.7 N/mm² end it was found that it was about 1.9 times of9.5 N/mm² of conventional concrete member formed of only normal concreteproduced on the same conditions.

                  TABLE X                                                         ______________________________________                                        (Weight   Normal      Normal   Light-weight                                   Parts )   concrete    Mortar   Mortar                                         ______________________________________                                        normal    100         100      100                                            Portland                                                                      cement                                                                        water     30          30       44                                             naphthol  2.5         2.2      1.0                                            high                                                                          quality                                                                       water                                                                         reduction                                                                     agent                                                                         fine      155         180      --                                             aggre-                                                                        gate A*                                                                       fine      130         --       --                                             aggre-                                                                        gate B**                                                                      light-    --          --       32                                             weight                                                                        aggre-                                                                        gate                                                                          (pear-                                                                        lite)                                                                         ______________________________________                                         *Ground sand of less than 5 mm particle diameter                              **Ground stone of 5 to 10 mm Particle diamter                            

EXAMPLE 32

Normal concrete having a size of 40 mm×40 mm×160 mm and composition ofTable X was molded and protected and cured in a steam atmosphere of 65°C. for four hours. The normal concrete after an age of 7 days has thereinforcing body of Example 31 adhered by epoxy resin adhesive to abottom thereof as shown in FIG. 3 to produce a concrete member. Aftercuring the adhesive, the concrete member was provided for bending testin accordance with JIS 5201.

As the result of the bending test, the flexural strength of the concretemember was 16.4 N/mm² and it was found that it was about 1.7 times of9.5 N/mm² of conventional concrete member formed of only normal concreteproduced on the same conditions.

EXAMPLE 33

As shown in FIG. 4, a box-like mold portion formed of reinforcing bodyof Example 31 having 2 mm thickness, 40 mm width and 160 mm length wassupported by the supporting member on the steel plate and partitioned atits end by plywood to form a permanent mold. In this permanent mold wasplaced normal mortar of Table X, which was protected in a steamatmosphere of 65° C. for 24 hours to produce a concrete member of 15 mmthickness, 40 mm width and 160 mm length having the reinforcing bodyintegrally associated therewith. The concrete member after an age of 7days was provided for bending test in accordance with JIS 5201.

As the result of the bending test, the flexural strength of the concretemember was 45.4 N/mm² and it was found that it was about 3.3 times of13.6 N/mm² of conventional member formed of only normal mortar producedon the same conditions.

EXAMPLE 34

The concrete member was produced and tested in the same manner as inExample 32, except for light-weight mortar used as material to be placedin place of normal concrete.

As the result of the bending test, the flexural strength of the concretemember was 17.8 N/mm² and it was found that it was about 4.9 times of3.6 N/mm² of conventional member formed of only light-weight mortarproduced on the same conditions. The concrete member of Example 34 hadspecific gravity of 1.69, which means that it was light.

EXAMPLE 35

A concrete member was produced in the same manner as in Example 31except for the reinforcing body placed in a steel mold as shown in FIG.5. The reinforcing body was formed by-forming therein a circular openingof 10 mm diameter (pitch of 20 mm) before being heated and thereafterbeing heated. The reinforcing body was supported by the spacer not shownin the steel mold of 15 mm thickness, 200 width and 200 mm length.

In the steel mold was placed normal mortar of Table X, which wasprotected in a steam atmosphere of 65° C. for four hours when 24 hourslapsed after the mortar was placed to produce the complete concretemember. The concrete member after its age of 7 days was cut into piecesof 40 mm width and 200 mm length and provided for bending tests inaccordance with JIS 5201.

As the result of the bending test, the flexural strength of the concretemember was 19.7 N/mm² and it was found that it was about 1.5 times of13.6 N/mm² of conventional concrete member formed of only mortarproduced on the same conditions.

EXAMPLE 36

A concrete member of 40 mm thickness, 40 mm width and 160 mm length wasproduced in the same manner as in Example 31. The reinforcing body wasdried at a temperature of 80° C. and thereafter was coated with epoxyresin on the surface thereof except for the surface of reinforcing body.After the thus obtained concrete member was immersed in water for onemonth, the water absorption thereof was measured. After that, it wasimmersed in a solution of 5% hydrochloric acid and the state of erosionwas observed. The conventional concrete member having no reinforcingbody of the invention provided therein was tested in the same manner.

As the result of the test, the water absorption of the concrete memberof Example 36 was 0.5% and the erosion of the surface thereof was notfound after it was immersed in the solution of 5% hydrochloric acid. Onthe other hand, the conventional concrete member formed of only concreteproduced on the same conditions had water absorption of 3.4% and thepaste of the conventional member was corroded after it was immersed in asolution of 5% hydrochloric acid. The conventional concrete member hadthe rough surface provided thereon.

As noted from Examples 31 to 36, the concrete member of the inventionhad higher flexural strength and as a result the reduced cross sectionand the light weight thereof were obtained. In addition thereto, it haddurabilities such as water tightness, chemical resistance and weatherresistance or salt damage resistance.

The concrete member of the invention can be applied to materials for aconstruction field such as footing, pillar, beam, floor materials,external wall materials, interior finishing material, materials forcivil engineering field such as canal, bridge, paving material, tunnel,tank and railing tie, materials for machinery field such as a base formachine tool, press die or the like.

Although some embodiments of the invention have been described andillustrated with and without reference to the accompanying drawings, itwill be understood by those skilled in the art that they are by way ofexamples, and that various changes and modifications may be made withoutdeparting from the spirit and scope of the invention.

What is claimed:
 1. A method of producing molding material comprisingthe step of mixing a cement composition having at least one kind ofhydraulic cement and a polymer precursor that is substantially anhydrousand generates water by a curing reaction, wherein said cementcomposition has from 12 to 60 parts by weight of said polymer precursorrelative to 100 parts by weight of said hydraulic cement, and whereinsaid cement composition is reactable in the absence of additional water.2. A method of producing molding material as set forth in claim 1,wherein said polymer precursor is formaldehyde resin precursor.
 3. Amethod of producing molding material as set forth in claim 1 furthercomprising the step of mixing an additive of a polymer having acid-amidebonding included therein with the hydraulic cement and the polymerprecursor.
 4. A method of producing molding material as set forth inclaim 1 wherein the hydraulic cement and the polymer precursor are inpowder form.
 5. A method of producing molding material as set forth inclaim 1 wherein the polymer precursor is in a thermally molten form. 6.A method of producing molding material as set forth in claim 1 whereinthe polymer precursor is in a form of alcohol solution.
 7. A method ofproducing a reinforced concrete member comprising the steps of:mixing acement composition having at least one kind of hydraulic cement and apolymer precursor that is substantially anhydrous and generates water bycuring reaction, wherein said cement composition has from 12 to 60 partsby weight of said polymer precursor relative to 100 parts by weight ofsaid hydraulic cement, and wherein said cement composition is reactablein the absence of additional water; shaping said cement composition;permitting said cement composition to react to form a hardenedreinforcing body; placing said reinforcing body in a mold; and placingand curing freshly mixed concrete in said mold to form said concretemember with said reinforcing body integrally associated therewith.
 8. Amethod of producing a concrete member as set forth in claim 7 whereinsaid polymer precursor is formaldehyde resin precursor.
 9. A method ofproducing a molded article comprising the step of mixing a cementcomposition having at least one kind of hydraulic cement and a polymerprecursor that is substantially anhydrous and generates water by acuring reaction, wherein said cement composition has from 12 to 60 partsby weight of said polymer precursor relative to 100 parts by weight ofsaid hydraulic cement, and wherein said cement composition is reactablein the absence of additional water,shaping said cement composition andpermitting said cement composition to react to form a hardened moldedarticle.
 10. A method of producing a molded article as set forth inclaim 9 further comprising the step of passing the hydraulic cement andthe polymer precursor through a pair of rollers after said mixing step.11. A method of producing a molded article as set forth in claim 9further comprising the step of heat pressing the hydraulic cement andthe polymer precursor after said mixing step.